When your with a group hiking in Sedona or visiting Disneyland it is a waste of time and might be a serious problem if you get separated. There could be an app for that. Everybody in the group downloads the app and turns it on. One, or more, people are designated as leaders and when you go to the app it shows you a local map with the location of all the group members.

It could be an add-on to existing apps like All Trails or even FitBit

So there is an obvious exit strategy after you create the MVP (minimum viable product) of the app.